rjw | 1f88458 | 2022-01-06 17:20:42 +0800 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (c) 2015 Travis Geiselbrecht |
| 3 | * |
| 4 | * Permission is hereby granted, free of charge, to any person obtaining |
| 5 | * a copy of this software and associated documentation files |
| 6 | * (the "Software"), to deal in the Software without restriction, |
| 7 | * including without limitation the rights to use, copy, modify, merge, |
| 8 | * publish, distribute, sublicense, and/or sell copies of the Software, |
| 9 | * and to permit persons to whom the Software is furnished to do so, |
| 10 | * subject to the following conditions: |
| 11 | * |
| 12 | * The above copyright notice and this permission notice shall be |
| 13 | * included in all copies or substantial portions of the Software. |
| 14 | * |
| 15 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
| 16 | * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
| 17 | * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. |
| 18 | * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY |
| 19 | * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, |
| 20 | * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE |
| 21 | * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
| 22 | */ |
| 23 | #include <lib/elf.h> |
| 24 | #include <assert.h> |
| 25 | #include <debug.h> |
| 26 | #include <endian.h> |
| 27 | #include <err.h> |
| 28 | #include <trace.h> |
| 29 | #include <stdlib.h> |
| 30 | #include <string.h> |
| 31 | #include <arch/ops.h> |
| 32 | |
| 33 | #define LOCAL_TRACE 0 |
| 34 | |
| 35 | struct read_hook_memory_args { |
| 36 | const uint8_t *ptr; |
| 37 | size_t len; |
| 38 | }; |
| 39 | |
| 40 | static ssize_t elf_read_hook_memory(struct elf_handle *handle, void *buf, uint64_t offset, size_t len) |
| 41 | { |
| 42 | LTRACEF("handle %p, buf %p, offset %lld, len %zu\n", handle, buf, offset, len); |
| 43 | |
| 44 | struct read_hook_memory_args *args = handle->read_hook_arg; |
| 45 | |
| 46 | DEBUG_ASSERT(args); |
| 47 | DEBUG_ASSERT(buf); |
| 48 | DEBUG_ASSERT(handle); |
| 49 | DEBUG_ASSERT(handle->open); |
| 50 | |
| 51 | ssize_t toread = len; |
| 52 | if (offset >= args->len) |
| 53 | toread = 0; |
| 54 | if (offset + len >= args->len) |
| 55 | toread = args->len - offset; |
| 56 | |
| 57 | memcpy(buf, args->ptr + offset, toread); |
| 58 | |
| 59 | LTRACEF("returning %ld\n", toread); |
| 60 | |
| 61 | return toread; |
| 62 | } |
| 63 | |
| 64 | status_t elf_open_handle(elf_handle_t *handle, elf_read_hook_t read_hook, void *read_hook_arg, bool free_read_hook_arg) |
| 65 | { |
| 66 | if (!handle) |
| 67 | return ERR_INVALID_ARGS; |
| 68 | if (!read_hook) |
| 69 | return ERR_INVALID_ARGS; |
| 70 | |
| 71 | memset(handle, 0, sizeof(*handle)); |
| 72 | |
| 73 | handle->read_hook = read_hook; |
| 74 | handle->read_hook_arg = read_hook_arg; |
| 75 | handle->free_read_hook_arg = free_read_hook_arg; |
| 76 | |
| 77 | handle->open = true; |
| 78 | |
| 79 | return NO_ERROR; |
| 80 | } |
| 81 | |
| 82 | status_t elf_open_handle_memory(elf_handle_t *handle, const void *ptr, size_t len) |
| 83 | { |
| 84 | struct read_hook_memory_args *args = malloc(sizeof(struct read_hook_memory_args)); |
| 85 | |
| 86 | args->ptr = ptr; |
| 87 | args->len = len; |
| 88 | |
| 89 | status_t err = elf_open_handle(handle, elf_read_hook_memory, (void *)args, true); |
| 90 | if (err < 0) |
| 91 | free(args); |
| 92 | |
| 93 | return err; |
| 94 | } |
| 95 | |
| 96 | void elf_close_handle(elf_handle_t *handle) |
| 97 | { |
| 98 | if (!handle || !handle->open) |
| 99 | return; |
| 100 | |
| 101 | handle->open = false; |
| 102 | |
| 103 | if (handle->free_read_hook_arg) |
| 104 | free(handle->read_hook_arg); |
| 105 | |
| 106 | free(handle->pheaders); |
| 107 | } |
| 108 | |
| 109 | static int verify_eheader(const struct Elf32_Ehdr *eheader) |
| 110 | { |
| 111 | if (memcmp(eheader->e_ident, ELF_MAGIC, 4) != 0) |
| 112 | return ERR_NOT_FOUND; |
| 113 | |
| 114 | if (eheader->e_ident[EI_CLASS] != ELFCLASS32) |
| 115 | return ERR_NOT_FOUND; |
| 116 | |
| 117 | #if BYTE_ORDER == LITTLE_ENDIAN |
| 118 | if (eheader->e_ident[EI_DATA] != ELFDATA2LSB) |
| 119 | return ERR_NOT_FOUND; |
| 120 | #elif BYTE_ORDER == BIG_ENDIAN |
| 121 | if (eheader->e_ident[EI_DATA] != ELFDATA2MSB) |
| 122 | return ERR_NOT_FOUND; |
| 123 | #endif |
| 124 | |
| 125 | if (eheader->e_ident[EI_VERSION] != EV_CURRENT) |
| 126 | return ERR_NOT_FOUND; |
| 127 | |
| 128 | if (eheader->e_phoff == 0) |
| 129 | return ERR_NOT_FOUND; |
| 130 | |
| 131 | if (eheader->e_phentsize < sizeof(struct Elf32_Phdr)) |
| 132 | return ERR_NOT_FOUND; |
| 133 | |
| 134 | #if ARCH_ARM |
| 135 | if (eheader->e_machine != EM_ARM) |
| 136 | return ERR_NOT_FOUND; |
| 137 | #elif ARCH_X86 |
| 138 | if (eheader->e_machine != EM_386) |
| 139 | return ERR_NOT_FOUND; |
| 140 | #elif ARCH_X86_64 |
| 141 | if (eheader->e_machine != EM_X86_64) |
| 142 | return ERR_NOT_FOUND; |
| 143 | #elif ARCH_ARM64 |
| 144 | if (eheader->e_machine != EM_AARCH64) |
| 145 | return ERR_NOT_FOUND; |
| 146 | #elif ARCH_MICROBLAZE |
| 147 | if (eheader->e_machine != EM_MICROBLAZE) |
| 148 | return ERR_NOT_FOUND; |
| 149 | #else |
| 150 | #error find proper EM_ define for your machine |
| 151 | #endif |
| 152 | |
| 153 | return NO_ERROR; |
| 154 | } |
| 155 | |
| 156 | status_t elf_load(elf_handle_t *handle) |
| 157 | { |
| 158 | if (!handle) |
| 159 | return ERR_INVALID_ARGS; |
| 160 | if (!handle->open) |
| 161 | return ERR_NOT_READY; |
| 162 | |
| 163 | // validate that this is an ELF file |
| 164 | ssize_t readerr = handle->read_hook(handle, &handle->eheader, 0, sizeof(handle->eheader)); |
| 165 | if (readerr < (ssize_t)sizeof(handle->eheader)) { |
| 166 | LTRACEF("couldn't read elf header\n"); |
| 167 | return ERR_NOT_FOUND; |
| 168 | } |
| 169 | |
| 170 | if (verify_eheader(&handle->eheader)) { |
| 171 | LTRACEF("header not valid\n"); |
| 172 | return ERR_NOT_FOUND; |
| 173 | } |
| 174 | |
| 175 | // sanity check number of program headers |
| 176 | LTRACEF("number of program headers %u, entry size %u\n", handle->eheader.e_phnum, handle->eheader.e_phentsize); |
| 177 | if (handle->eheader.e_phnum > 16 || handle->eheader.e_phentsize != sizeof(struct Elf32_Phdr)) { |
| 178 | LTRACEF("too many program headers or bad size\n"); |
| 179 | return ERR_NO_MEMORY; |
| 180 | } |
| 181 | |
| 182 | // allocate and read in the program headers |
| 183 | handle->pheaders = calloc(1, handle->eheader.e_phnum * handle->eheader.e_phentsize); |
| 184 | if (!handle->pheaders) { |
| 185 | LTRACEF("failed to allocate memory for program headers\n"); |
| 186 | return ERR_NO_MEMORY; |
| 187 | } |
| 188 | |
| 189 | readerr = handle->read_hook(handle, handle->pheaders, handle->eheader.e_phoff, handle->eheader.e_phnum * handle->eheader.e_phentsize); |
| 190 | if (readerr < (ssize_t)(handle->eheader.e_phnum * handle->eheader.e_phentsize)) { |
| 191 | LTRACEF("failed to read program headers\n"); |
| 192 | return ERR_NO_MEMORY; |
| 193 | } |
| 194 | |
| 195 | LTRACEF("program headers:\n"); |
| 196 | uint load_count = 0; |
| 197 | for (uint i = 0; i < handle->eheader.e_phnum; i++) { |
| 198 | // parse the program headers |
| 199 | struct Elf32_Phdr *pheader = &handle->pheaders[i]; |
| 200 | |
| 201 | LTRACEF("%u: type %u offset 0x%x vaddr 0x%x paddr 0x%x memsiz %u filesize %u\n", |
| 202 | i, pheader->p_type, pheader->p_offset, pheader->p_vaddr, pheader->p_paddr, pheader->p_memsz, pheader->p_filesz); |
| 203 | |
| 204 | // we only care about PT_LOAD segments at the moment |
| 205 | if (pheader->p_type == PT_LOAD) { |
| 206 | // if the memory allocation hook exists, call it |
| 207 | void *ptr = (void *)(uintptr_t)pheader->p_vaddr; |
| 208 | |
| 209 | if (handle->mem_alloc_hook) { |
| 210 | status_t err = handle->mem_alloc_hook(handle, &ptr, pheader->p_memsz, load_count, 0); |
| 211 | if (err < 0) { |
| 212 | LTRACEF("mem hook failed, abort\n"); |
| 213 | // XXX clean up what we got so far |
| 214 | return err; |
| 215 | } |
| 216 | } |
| 217 | |
| 218 | // read the file portion of the segment into memory at vaddr |
| 219 | LTRACEF("reading segment at offset %u to address %p\n", pheader->p_offset, ptr); |
| 220 | readerr = handle->read_hook(handle, ptr, pheader->p_offset, pheader->p_filesz); |
| 221 | if (readerr < (ssize_t)pheader->p_filesz) { |
| 222 | LTRACEF("error %ld reading program header %u\n", readerr, i); |
| 223 | return (readerr < 0) ? readerr : ERR_IO; |
| 224 | } |
| 225 | |
| 226 | // zero out he difference between memsz and filesz |
| 227 | size_t tozero = pheader->p_memsz - pheader->p_filesz; |
| 228 | if (tozero > 0) { |
| 229 | uint8_t *ptr2 = (uint8_t *)ptr + pheader->p_filesz; |
| 230 | LTRACEF("zeroing memory at %p, size %zu\n", ptr2, tozero); |
| 231 | memset(ptr2, 0, tozero); |
| 232 | } |
| 233 | |
| 234 | // make sure the i&d cache are coherent, if they exist |
| 235 | arch_sync_cache_range((addr_t)ptr, pheader->p_memsz); |
| 236 | |
| 237 | // track the number of load segments we have seen to pass the mem alloc hook |
| 238 | load_count++; |
| 239 | } |
| 240 | } |
| 241 | |
| 242 | // save the entry point |
| 243 | handle->entry = handle->eheader.e_entry; |
| 244 | |
| 245 | return NO_ERROR; |
| 246 | } |
| 247 | |